The invention relates to cellophaning machines intended to wrap in packaging film pre-packaged products provided with a transverse strip for tearing open the said packaging when the packaged product is used. In particular the invention relates to those machines in which the tearing strip is adhesive and is fed transversely with respect to the direction of feeding of the packaging film.
In this technical sector, the state of the art is at present represented by the solution shown schematically and in perspective in FIG. 1 of the accompanying drawings, where 1 indicates the packaging film which is unwound from a reel (not shown) and which is usually made to advance with an intermittent movement by suitable means in the direction indicated by the arrow 2. A belt-type conveyor 3 is arranged transversely underneath the film, said conveyor being usually formed by a toothed belt which is driven on toothed horizontal-axis pulleys 103 and which has an upper section located parallel to and at an appropriate distance from the film 1 and, by suitable means acting on one of the pulleys 103, is made to advance with an intermittent movement in the direction, for example, of the arrow 4. The upper section of the belt 3 slides sealingly on a straight and fixed manifold 6 which is connected at 106 to a suction source such that, via through-holes 5 of the belt, the upper section of the belt itself is constantly sucked and is able to retain and convey the tearing strip 7 which has an adhesive upper side and is unwound from a reel, not shown, and which, by means of jockey rollers, also not shown, and motor-driven drawing rollers 8 and transmission rollers 9 is fed with the correct orientation and at the correct speed on the said belt 3. Usually, the linear feeding speed of the belt 3 is suitably greater than the peripheral speed of the drawing rollers 8 so that the strip 7 is extended longitudinally on the said conveyor belt. A small wedge 10 is provided on the side of the film 1 and at an appropriate distance from the latter, on the upper section of the conveyor belt 3, substantially in contact therewith, which wedge is fixed to the base of the machine and is directed with its thickest part towards the film 1 and onto which the strip 7 rises and then descends, and a cutter 11 rotating on a horizontal axis 111 is also provided, said cutter interfering in synchronism with the top part of the wedge 10 in order to cut transversely the section of strip 7 to be positioned underneath the film 1, by an amount which is proportional to the width of the said film. Once cutting has been performed, when the cut strip section 7 has been correctly positioned underneath the film 1, the conveyor belt 3 stops and a pressing device 12 which is made of resiliently yielding material and is spring-loaded intervenes, said pressing device pushing the film 1 against the belt 3 so as to attach the tearing strip 7 to the said film, following which the pressing device is raised and the film 1 with the tearing strip is inserted into the packaging machine and the cycle described is repeated.
The front end of the tearing strip which, after the action of the cutter 11, is arranged on the top of the inclined surface 10, is not subject to the action of the suction holes 5 and is difficult to control and often follows the said rotating cutter 11, with all the drawbacks which are imaginable.
The invention intends to overcome these and other problems of the known art, with the following proposed solution. The cutting means 11-111 are eliminated and suitable cutting means are associated with the body of the pressing device 12, while the conveyor belt 3 is used also to perform the function of a cutter counter-piece.